I Put two cupfuls of white stock into a saucepan with half a dozen mushrooms, chopped fine, a two-inch strip of lemon-peel, salt and pepper to season, and a teaspoonful of minced parsley. Simmer for an hour and strain. Thicken with a teaspoonful of flour, rubbed smooth in a little cold stock or water, take from the fire, and add the yolks of three eggs beaten with the juice of half a lemon. Reheat, but do not boil. Take from the fire and add a tablespoonful of butter.